1. Field of the Invention
The present invention relates to a work-vehicle cabin having an air-conditioning unit mounted to a ceiling portion of the cabin, the air-conditioning unit having a heater and an evaporator.
2. Description of the Related Art
A work-vehicle cabin having an air-conditioning unit is known from Japanese Patent Application “Kokai” No.: Hei. 8-216672 (see paragraph [0020], FIGS. 1 and 2). In this, a downwardly bulging ceiling portion includes a forward air-supply opening, rearwardly of which there is disposed an air-conditioning unit for feeding conditioned air to this forward air-supply opening. In the case of this conventional cabin, the forward air-supply opening and the air-conditioning unit are disposed one behind the other. So, the air-conditioning unit projects rearward significantly. As a result, the rear end the downwardly bulging ceiling portion extends to a position upwardly of a driver's seat, thus compromising roominess of the cabin and driver's comfort. Further, in this cabin, for connecting a front air-conditioning duct for guiding conditioned air to right and left ends and lateral air-conditioning ducts for receiving the conditioned air from the front air-conditioning duct, inclined flanges provided in the respective ducts is employed (paragraph [0018], FIG. 3). This connecting construction using inclined flanges tends to result in displacement between the flanges, which leads eventually to air leak from the connection.
For mounting the air-conditioning unit in the work-vehicle cabin, a shutter mechanism is required as a damper for switching between indoor air and outdoor air. In this regard, Japanese Patent Application “Kokai” No.: Hei. 2-148816 (page 5, line 12 through page 6, line 15) discloses a construction wherein this shutter is supported to be pivotable about a lateral axis to be raised and lowered and for this shutter, a knob acting as a switchover mechanism is connected via a push/pull wire, so that the shutter is switched over by an operator's pulling/pushing the wire with gripping the knob. With such air switchover damper, when this damper is set to a first condition for introducing outdoor air by closing an air circulating opening, if an operator entering or exiting the cabin opens the entrance door of the cabin and then closes it again, this closing action causes momentary compression of the air inside the cabin, and this increased inside pressure may automatically or inadvertently switch over the damper from the first condition to a second condition. In order to avoid such inadvertent switchover, it is necessary to provide a moving resistance to the operational portion of the knob, so that the damper may effectively resist such automatic switchover. In this case, the resistance gives a heavy feel for the operator in the switchover operation.
As disclosed by e.g. Japanese Patent Application “Kokai” No.: 2000-347666 (paragraph [0016], FIGS. 1 and 2), the work-vehicle cabin often includes, at right and left sides thereof, windows which can be opened to the outside In such construction, because of insufficient overlap of the roof portion over these windows, there tends to occur blowing-in of raindrops or the like when the windows are opened to the outside.